Goes without saying…
Using Buddy Bearings and NOT submersing the wheels in saltwater or any water if possible is prudent.
I have lots of miles on 8" tires.
The trick is if you carry a spare tire and set of bearings you will never need them.
Installing a spare set of bearings
– Last Updated: Sep-02-14 9:18 AM EST –
How does the average person install the outer races when replacing bearings on the side of the road? You can knock the old ones out with a hammer and punch, but installing new races without a press is iffy at best (odds are really good that they'll end up with slight deformities near the edges). As you say, you probably won't ever need them, but what's the plan if you do? Do you carry a bunch of clean rags and spare grease too?
One other advantage of 12" wheels
Dear Larry,
One other advantage of a trailer with 12" wheels is the increased ground clearance and the greater ability to travel rough and rutted roads.
If you are often traveling dirt and gravel roads to launch and recover your boats that can be a big advantage.
While you probably won’t damage your trailer frame or the boats you are hauling it is quite easy to bottom out and damage or lose your license plate and/or damage the trailer lights.
Regards,
Tim Murphy AKA Goobs
15" inch wheels
Do yourself a favor and get a high quality trailer with 15" wheels. One factor that will cause bearing failure is heat. Heat is caused by excessive speed, which is what goes on with small wheels. Even in the best of environments, bearings will not last forever, but generally in the larger wheels they will probably last a very long time with reasonable maintenance.
diminishing returns
– Last Updated: Sep-02-14 10:54 AM EST –
One would think at some point, the greater mass of the larger wheel, and the resultant greater wear or load on the bearings, would offset the reduced wear from using a bigger wheel. This is why guys who drive trucks with 22" rims are not very bright.
My first car had 13" wheels. Never replaced a wheel bearing.
Agree
I had a car with 13-inch rims too. I drove it for almost 200,000 miles, and though I did re-grease the wheel bearings a few times over that time span, plenty of other people would not have and still would have had a good chance of the bearings lasting.
Another problem with 15-inch wheels, is that any trailer axle having hubs that will accept 15-inch wheels will be very heavy-duty. It won’t be practical to put such an axle on a light trailer with light springs, so most likely this would mean using a heavy-duty trailer. There’s no reason to subject bikes and boats to the ride-quality of an essentially unloaded heavy-duty trailer.
As far as heat reduction goes, note from Pikabike’s post that properly lubricated (and properly adjusted) bearings don’t get hot, not even on 8-inch rims. Speed of rotation isn’t the whole story, since there are other bearings with long lifespans that spin many times faster than those on trailer wheels.
that’d be my concern
…with a 15" wheel, agree about this aspect.
Speed vs RPM
– Last Updated: Sep-02-14 12:43 PM EST –
At 60 MPH a 8 inch wheel is going about 2500 RPM and a 13 inch wheel is going about 1680 RPM. However the bearing size it self may make those numbers closer (not in the actual speed but what RPM they are good for) as a smaller bearing can normally rotate faster than a larger one. Ball bearings can go faster than tapered roller bearings, oil lube faster than grease and oil mist even faster than oil. All of that has to do with heat. I will have misspent 43 years in the bearing business this fall and pretty much seen every bearing failure known but lubrication issues both too much and too little and heat top my list.
I was thinking about bearing-size …
– Last Updated: Sep-02-14 12:57 PM EST –
... differences, since the larger the bearing, the faster the rollers must travel (spin) for a given wheel RPM. Fortunately, this discussion seems mostly to be centered on whether to put 8-inch or 12-inch wheels on the same hub, meaning the same bearings would be used in either case.
In regard to your other comments, I have often wondered about the reasons many modern truck wheel bearings are bathed in oil instead of being packed with grease. Sounds like you'd be a person who'd know. I won't insist on delving into that right here, but feel free if there's such a thing as a concise answer.
Actually
With taper roller bearings the same bearing, say with a 1 inch bore, could use up to a dozen different races of different OD’s. When I say bearing size I am referring to the ID and OD added together and divided by 2 to get the center line which we use to get what we bearing people call the DN value which tells us the limiting speed based on lube type. Anyway the 8 inch wheel could have a smaller bearing on not. The biggest problem in trailer bearing’s is where they are made and today most of them come from a very large Asian country that cost much less than domestic bearings.
Thanks for clarifying what “size” means
– Last Updated: Sep-02-14 1:28 PM EST –
I've never pretended to understand the terminology of bearing sizes (thank goodness they are stamped with a number that allows me to "ask someone who knows" when replacement is needed).
Still, when the people here talk about interchanging 8-inch and 12-inch wheels on the same hub, the bearing that's used will always be the same, which was all I was saying in my previous post (they aren't switching hubs or the bearings within the hub - they are only switching wheels).
Oh, and are you saying the quality of bearings made in China isn't always as good as it could be? Who'da thunk it? (hee-hee)
and 3rd party auto wheel bearings
I learned the hard way not to skimp on wheel bearings on my last car. Now THAT was time and money misspent!
Bigger wheels=better chance to avoid
any sort of road debris from fresh accidents.
I try to avoid the freeways here but must use them for some routes to put- ins, and I have been really grateful for the higher clearance of 4 wh drive every time I’ve been forced to run over and straddle something that wasn’t picked up yet because there was no way I could change lanes in time. And driving here, even if you do slow down, means that crazy people are ALWAYS weaving in and out as if they’re in a video game, trying to get by and you have to be super vigilant to avoid their stupidity.
I’ve seen lots of boat trailers along side the road, too, with a wheel missing… they are usually parked southbound, which means that they broke down on the way back from the lake(s), and they didn’t make it with the Barbie Wheels. Not how I’d want to spend my Sunday evening…
Love my Dexter EZ-lube axles
On my first trailer I got over 60,000 miles and never had a problem.
I traded it in and now I am on my second one with the same type.
One tube of grease will do four wheels and it is a nice simple procedure.
Jack L
I have 8" on my
1969 Montgomery Ward Western Field tent trailer. I can’t remember how many miles I’ve put on it, but it has traveled a lot over the years. American bearings and good care probably have much to do with success. Also, I use the high temperature disk brake grease, not normal ball joint grease. It semi retired for a while, then made a few more trips, and is waiting conversion to a boat hauler. Quality parts and good care make all of the difference.
Size
Size is still the ID and OD and with. We only use the DN value when looking for the max speed. Not something we do every day either, most of the time it is when some Gyro Gearloose is going to reinvent something.
Lots of factors
As Old Bill is well aware, one of the engineering aspects that is considered in bearing application is a theoretical maximum number of revolutions a bearing can be expected to do in its lifetime. Smaller wheel and tire equals lots more revolutions per mile than a bigger wheel, so everything else being fairly equal, the bearings in the larger diameter wheel should last much longer.
All of this is just jibber jabber anyway. The point is that up to a point, the bigger wheels should equal more reliability and a safer ride for your boat. The idea of an itty bitty trailer with itty bitty wheels ripping along down a freeway with expensive boats on it doesn’t work for me.
15" is overkill
…and you’re going to pay a premium for the axle, in weight, and eventually when you go to replace tires.
A taller wheel presents greater lateral forces on a turn than a shorter wheel.
I think you should think the “bigger is better” thing through some more.
Disk brake grease?
I use automotive wheel bearing grease.
wheels
I doubt trailer manufacturers would use 8" wheels if there were serious concerns about their ability to handle highway speeds.
That being said, I don’t understand why they ALL don’t just use 12" wheels. The cost difference in the overall trailer cost would be minor.